The present invention relates to the dispatch of a plurality of electrical generation systems accessible over a computer network. More specifically, the invention is directed towards those generation systems classified as xe2x80x9cdistributed generatorsxe2x80x9d, or xe2x80x9cdistributed resourcesxe2x80x9d that can be remotely monitored and activated by a central controller over a global computer network. For the purposes of this disclosure, a distributed generator/resource is any small-scale electricity-generating device producing maximum power of less than 20 MW as defined in decision 99-10-065 of the Public Utilities Commission of the State of California.
Presently, in some states in the United States, the demand for electricity at given times during the year exceeds the present capacity of the electric utility provider within the given area. The lack of energy capacity can result in brownouts or blackouts in these areas. In response to this problem, distributed generation resources can be connected to the power grid to provide supplemental energy resources at times of high demand. Typically, the distributed generation resources are capable of being remotely monitored and activated by the utility or other controlling agent.
As distributed generation resources are being widely deployed and used in the modern energy markets, there is a need to deploy large groups of generators that may be of a wide variety of makes and models. The order in which the generators are started and begin generating power will have an effect on maintenance costs, operating costs, and performance. The determination of start order is based upon a significant number of variables that vary from one make and model of generator to another. Thus, there is a need to determine the order in which to dispatch a plurality of generators that takes into account multiple variables in the decision making process.
Decision-making is a process that lends itself to a series of rules. These rules are classically implemented using a series of if-then statements. While these rules are effective for go/no-go decisions, ordering and ranking based upon multiple variables proves to be a task too complicated to effectively implement using classic programming techniques. Ranking is a somewhat simple task if only one variable is being accounted for. However, appropriate ordering becomes ambiguous if multiple factors are being considered. Historically, either simple, single variable sorting has been used or complex, non-editable equations were used to determine the order in which generators were to be started. Both of these methodologies have drawbacks. Single variable sorting ignores most variables in what is in actuality a very complex decision. The use of non-editable equations requires an expert to create a mathematical relationship between input variables and sort order. This method is not updateable and requires different equations for different generator types and will not accurately sort generators of different makes and models.
Therefore, a need exists for a system and method for determining the order in which distributed generation resources are deployed that takes into account multiple ranking variables in an automated and efficient manner. Further, a need exists for a method of initiating the activation of distributed generation resources that can be modified according to revised parameters without requiring entirely new equations and determination factors.
The present invention relates to a system and method for dispatching a plurality of distributed electrical generation systems that are accessible over a computer network. A central computer controller monitors each of the distributed generation systems and initiates operation of each generation system based upon the current ranking of the generation system relative to the other generation systems. The ranking of each system is based upon multiple variables received by the central controller. Based upon these multiple input variables, the central controller utilizes a series of predefined linguistic rules to rank each of the generators and start the generators based upon the ranking order.
The ranking and dispatch system of the present invention is able to account for an unlimited number of parameters and input variables in the ranking process. Further, the ranking and dispatch system of the present invention works for any combination of generator makes and models, since each make and model has its own specific set of rules to define the ranking order. Further, the ranking and dispatch system of the present invention does not require knowledge of system mathematics to configure and generate the ranking order.
The ranking and dispatch system of the present invention utilizes a fuzzy logic engine to perform approximate reasoning. Approximate reasoning implements a series of rules in the form of xe2x80x9cif-thenxe2x80x9d statements. For example, a rule implemented in accordance with the present invention may be xe2x80x9cIf run time hours are high and fuel costs are high, then rank is low.xe2x80x9d
Before the ranking and dispatch system can generate a ranking, the linguistic variables must first be set. In a generator dispatch system, fuel volume, run time hours, fuel costs, operating efficiency and other important operating characteristics can be set as the linguistic variables for the system. The linguistic variables can vary for each type of generator.
After the linguistic variables are determined, the terms and hedges are set for each variable. Typically, terms such as high, medium and low are used for each of the linguistic variables, such that the variables can be classified easily.
After the terms and hedges have been set, the consequent linguistic variable is determined. In the present invention, the consequent linguistic variable is xe2x80x9crankxe2x80x9d and includes the terms xe2x80x9chighxe2x80x9d, xe2x80x9cmediumxe2x80x9d, xe2x80x9clowxe2x80x9d. Thus, once the rules are defined, the result is that the consequent variable rank is either high, medium or low.
With the terms and hedges, consequent linguistic variable and input variables set, the user enters various rules into the ranking and dispatch system. These rules are typically xe2x80x9cif-thenxe2x80x9d statements that relate the variables to a rank. As indicated, one rule could be: If run time hours are high and fuel cost is high, then rank is low.
Once the rules have been set, the input data is normalized. With the data normalized, approximate or fuzzy reasoning is applied to each item to be ranked. As indicated, the normalized data is then entered into one of the rules and the consequent linguistic variable rank is determined to be either high, medium or low. Once this variable for the ranking has been set, the various generators are ordered from highest rank to lowest rank.
In accordance with the ranking and dispatch system of the present invention, the rules are not limited to the number of variables (antecedent terms), nor does the system limit the number of rules that may be used to determine rank. Thus, the system is capable of handling any number of input parameters.
Because approximate reasoning implements representations of linguistic rules, the mathematics of the system may remain transparent from the users. Users need only to establish a set of linguistic rules for each make and model of the generator.
Once the various generators are ranked, the computerized control system initiates activation of each generator based upon the ranking. In this manner, the computerized controller is able to effectively activate the most preferred generator prior to activation of less preferred generators.
The methodology of the present invention is to be implemented with an n-tier thin client architecture in which the variables and rules are configured through a web interface communicating with compiled business logic components on a central server. The rules are to be stored in a database residing on the server or servers. The process of data normalization and ranking will be performed within a business logic tier. Generators may then be dispatched using a communication engine to directly communicate with the distributed resources over a network, either local or wide area.